make shure IO streams are flushed before exiting a process.

wait for forked streams to end before resolving promise
(cherry picked from commit 4539ccc)

wait for io streams to end even when fork promise is rejected
(cherry picked from commit 6bff82a)

Author: jamestalmage

cli.js

@@ -51,7 +51,7 @@ var errors = [];
 
 function error(err) {
 	console.error(err.stack);
-	process.exit(1);
+	flushIoAndExit(1);
 }
 
 function prefixTitle(file) {
@@ -167,13 +167,22 @@ function exit(results) {
 		log.errors(flatten(tests));
 	}
 
+	process.stdout.write('');
+
+	flushIoAndExit(
+		failed > 0 || unhandledRejectionCount > 0 || uncaughtExceptionCount > 0 ? 1 : 0
+	);
+}
+
+function flushIoAndExit(code) {
 	// TODO: figure out why this needs to be here to
 	// correctly flush the output when multiple test files
 	process.stdout.write('');
+	process.stderr.write('');
 
-	// timeout required to correctly flush stderr on Node 0.10 Windows
+	// timeout required to correctly flush io on Node 0.10 Windows
 	setTimeout(function () {
-		process.exit(failed > 0 || unhandledRejectionCount > 0 || uncaughtExceptionCount > 0 ? 1 : 0);
+		process.exit(code);
 	}, 0);
 }